Porous Unit-Cell Padding for High-Strain-Rate Impact Absorption
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Solution Overview
Problem
Current padding materials, including second skin products, are inadequate in absorbing energy during high-strain-rate impacts common in sporting activities, as they rapidly stiffen and fail to attenuate impact energy effectively.
Innovation Solution
A padding material composed of a cured polymeric base with raised unit cells and an embedded textile substrate, featuring fine porosity and breathability, which allows for improved shock absorption and adhesion to the skin, and can be produced using a method involving a two-part mold and vacuum curing to create a matrix with protruding unit cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional foam cell materials or gel-like substances are used for padding, then the padding can attenuate impact energy at low strain rates, but at high strain rates the materials rapidly stiffen and fail to absorb impact energy effectively
Solution Approach 1:
The padding material is segmented into an array of discrete, spaced-apart unit cells rather than a continuous foam structure. Each unit cell independently deforms during impact, preventing the rapid stress propagation and stiffening that occurs in continuous foam materials at high strain rates. This segmentation allows the padding to maintain energy absorption capability across a wider range of strain rates.
Solution Approach 2:
The unit cells are formed from a porous polymeric material with controlled porosity. The porous structure allows for gradual compression and deformation during impact, enabling the material to absorb energy effectively even at high strain rates where conventional dense foams would rapidly stiffen. The porosity provides compressibility while maintaining structural integrity.
2Adaptability or versatility
If a substrate is embedded in the polymeric material to provide adhesion and breathability, then the padding can adhere to skin and allow air permeation, but the manufacturing process becomes more complex
Solution Approach 1:
The substrate and polymeric unit cells are merged into a single integrated structure during the molding process. The substrate is positioned within the mold cavity, and the polymeric material is then formed around and through the substrate in one continuous operation. This eliminates the need for separate assembly steps to attach the substrate to the padding, reducing manufacturing complexity while maintaining both adhesion and breathability functions.
Solution Approach 2:
The substrate serves multiple functions simultaneously: it provides adhesion to the skin, allows air permeation for breathability, and acts as a structural support for the unit cells. By integrating these multiple functions into a single component, the design reduces the number of separate parts and assembly steps required, simplifying the overall manufacturing process.
3Loss of energy
If the unit cells are spaced apart rather than continuous, then the padding can reduce high-strain-rate stiffening, but the manufacturing precision required to ensure proper cell formation and spacing increases
Solution Approach 1:
The mold cavity is pre-configured with the exact geometry and spacing of the unit cells before the polymeric material is introduced. This preliminary preparation of the mold ensures that when the material is formed, the unit cells are automatically created with precise spacing and uniform dimensions. The pre-designed mold structure guides the material flow and cell formation, reducing the precision requirements during the actual molding process.
Solution Approach 2:
The manufacturing process utilizes controlled changes in pressure and temperature parameters during molding to facilitate proper unit cell formation. By adjusting these parameters, the process accommodates variations in material properties and mold tolerances, ensuring consistent unit cell geometry and spacing without requiring extremely tight manufacturing tolerances. The material's rheological properties are optimized to flow into and fill the mold cavity uniformly.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The padding material demonstrates enhanced energy absorption capabilities compared to conventional products, with reduced high-strain-rate stiffening and improved breathability, enabling better protection and customizable fit, and can include embedded sensors for wear indication.
Implementation Method 1
The present invention provides padding materials suitable for use as or incorporation into various protective products... capable of energy absorption to offer protection from impacts
Implementation Method 2
padding materials that include an array of shock absorbing surface features integrated into and protruding from a substrate
Implementation Method 3
The base and the unit cells are formed of a cured polymeric material that contains fine porosity
Implementation Method 4
a substrate formed of a textile or fabric material is embedded in the base and permeated by the cured polymeric material
Implementation Method 5
generating a vacuum through the second component such that a first portion of the uncured polymer material is siphoned from the recesses in the first component and through the substrate
Implementation Method 6
a first portion of the uncured polymer material is siphoned from the recesses in the first component and through the substrate
Implementation Method 7
curing the uncured polymer material to form a cured polymeric material that is integrated into and permeates the substrate
Data Source
AI summary
Padding materials capable of use as or incorporation into protective products, and methods of producing such padding materials. The padding material includes a base and an array of raised unit cells that individually protrude from a surface of the base so that the unit cells are spaced apart from each other. The base and the unit cells are formed of a cured polymeric material that contains fine porosity, and a substrate formed of a textile or fabric material is embedded in the base and permeated by the cured polymeric material.